[ONOS-4438] Add REST API for mastership service

- Correct some typos in mastership codec

Change-Id: If8a0127d8d897d4b87cae71a194dfece6aa14f49
diff --git a/web/api/src/main/resources/definitions/RoleInfo.json b/web/api/src/main/resources/definitions/RoleInfo.json
new file mode 100644
index 0000000..55e1e9d
--- /dev/null
+++ b/web/api/src/main/resources/definitions/RoleInfo.json
@@ -0,0 +1,25 @@
+{
+  "type": "object",
+  "title": "roleInfo",
+  "required": [
+    "master",
+    "backups"
+  ],
+  "properties": {
+    "master": {
+      "type": "string",
+      "example": "1"
+    },
+    "backups": {
+      "type": "array",
+      "xml": {
+        "name": "backups",
+        "wrapped": true
+      },
+      "items": {
+        "type": "string",
+        "example": "1"
+      }
+    }
+  }
+}
\ No newline at end of file